The invention generally relates to heat exchangers, and more specifically to a recuperative heat exchanger particularly suited for reducing the power required in maintaining reactive temperatures within systems utilized for the reduction of CO.sub.2, through a process known as the Bosch process, aboard spacecraft and similar vehicles.
In the Bosch process CO.sub.2 is catalytically reacted with H.sub.2 to form water and solid carbon. In space applications, the water is electrolyzed to return O.sub.2 to the crew of the spacecraft and H.sub.2 is returned to the reduction unit.
The reaction of CO.sub.2 with H.sub.2 takes place at 1100.degree. to 1300.degree. F. but cannot be completed efficiently in a single pass because a water vapor equilibrium is approached. Therefore, a recylce system is preferred. Such a system normally comprises a closed loop in which the carbon can be accumulated with a catalyst cartridge for periodic removal, water vapor can be removed continuously by condensation and feed gases can enter only to replace the volume reductions due to the reaction and to water condensation and separation.
In practice, a recuperative heat exchanger is employed for reducing the power required in maintaining reactive temperatures. As can be appreciated, heat exchangers having conventional configurations are limited in effectiveness by the combination of space limitations, longitudinal temperature gradients, and recycle pumping power capabilities. A further objection to heat exchangers heretofore employed is that most of the materials utilized in the fabrication of such heat exchangers are especially catalytically active in weld areas. This, of course, results in a formation and collection of carbon which tends to block the passages of the heat exchanger, to the extent that rupture may be experienced. Moreover, in the aerospace industry, the envelope size as well as the mass of system components is of utmost concern to designers. Therefore, use of heat exchangers of conventional configurations in a space environment is impaired due to both bulk and consideration given to weight limitations.
It is therefore the general purpose of the instant invention to provide a compact, lightweight heat exchanger characterized by an increased achievable heat exchange effectiveness, and an increased operational life span.